Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core
An important share of paleoclimatic information is buried within the lowermost layers of deep ice cores. Because improving our records further back in time is one of the main challenges in the near future, it is essential to judge how deep these records remain unaltered, since the proximity of the b...
Published in: | The Cryosphere |
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Copernicus Publications
2015
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Online Access: | https://doi.org/10.5194/tc-9-1633-2015 https://doaj.org/article/cab145aa982247b4b545297f06bfa72b |
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ftdoajarticles:oai:doaj.org/article:cab145aa982247b4b545297f06bfa72b 2023-05-15T14:00:05+02:00 Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core J.-L. Tison M. de Angelis G. Littot E. Wolff H. Fischer M. Hansson M. Bigler R. Udisti A. Wegner J. Jouzel B. Stenni S. Johnsen V. Masson-Delmotte A. Landais V. Lipenkov L. Loulergue J.-M. Barnola J.-R. Petit B. Delmonte G. Dreyfus D. Dahl-Jensen G. Durand B. Bereiter A. Schilt R. Spahni K. Pol R. Lorrain R. Souchez D. Samyn 2015-08-01T00:00:00Z https://doi.org/10.5194/tc-9-1633-2015 https://doaj.org/article/cab145aa982247b4b545297f06bfa72b EN eng Copernicus Publications http://www.the-cryosphere.net/9/1633/2015/tc-9-1633-2015.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 1994-0416 1994-0424 doi:10.5194/tc-9-1633-2015 https://doaj.org/article/cab145aa982247b4b545297f06bfa72b The Cryosphere, Vol 9, Iss 4, Pp 1633-1648 (2015) Environmental sciences GE1-350 Geology QE1-996.5 article 2015 ftdoajarticles https://doi.org/10.5194/tc-9-1633-2015 2022-12-31T13:30:08Z An important share of paleoclimatic information is buried within the lowermost layers of deep ice cores. Because improving our records further back in time is one of the main challenges in the near future, it is essential to judge how deep these records remain unaltered, since the proximity of the bedrock is likely to interfere both with the recorded temporal sequence and the ice properties. In this paper, we present a multiparametric study (δD-δ 18 O ice , δ 18 O atm , total air content, CO 2 , CH 4 , N 2 O, dust, high-resolution chemistry, ice texture) of the bottom 60 m of the EPICA (European Project for Ice Coring in Antarctica) Dome C ice core from central Antarctica. These bottom layers were subdivided into two distinct facies: the lower 12 m showing visible solid inclusions (basal dispersed ice facies) and the upper 48 m, which we will refer to as the "basal clean ice facies". Some of the data are consistent with a pristine paleoclimatic signal, others show clear anomalies. It is demonstrated that neither large-scale bottom refreezing of subglacial water, nor mixing (be it internal or with a local basal end term from a previous/initial ice sheet configuration) can explain the observed bottom-ice properties. We focus on the high-resolution chemical profiles and on the available remote sensing data on the subglacial topography of the site to propose a mechanism by which relative stretching of the bottom-ice sheet layers is made possible, due to the progressively confining effect of subglacial valley sides. This stress field change, combined with bottom-ice temperature close to the pressure melting point, induces accelerated migration recrystallization, which results in spatial chemical sorting of the impurities, depending on their state (dissolved vs. solid) and if they are involved or not in salt formation. This chemical sorting effect is responsible for the progressive build-up of the visible solid aggregates that therefore mainly originate "from within", and not from incorporation processes of debris ... Article in Journal/Newspaper Antarc* Antarctica EPICA ice core Ice Sheet The Cryosphere Directory of Open Access Journals: DOAJ Articles The Cryosphere 9 4 1633 1648 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 J.-L. Tison M. de Angelis G. Littot E. Wolff H. Fischer M. Hansson M. Bigler R. Udisti A. Wegner J. Jouzel B. Stenni S. Johnsen V. Masson-Delmotte A. Landais V. Lipenkov L. Loulergue J.-M. Barnola J.-R. Petit B. Delmonte G. Dreyfus D. Dahl-Jensen G. Durand B. Bereiter A. Schilt R. Spahni K. Pol R. Lorrain R. Souchez D. Samyn Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
An important share of paleoclimatic information is buried within the lowermost layers of deep ice cores. Because improving our records further back in time is one of the main challenges in the near future, it is essential to judge how deep these records remain unaltered, since the proximity of the bedrock is likely to interfere both with the recorded temporal sequence and the ice properties. In this paper, we present a multiparametric study (δD-δ 18 O ice , δ 18 O atm , total air content, CO 2 , CH 4 , N 2 O, dust, high-resolution chemistry, ice texture) of the bottom 60 m of the EPICA (European Project for Ice Coring in Antarctica) Dome C ice core from central Antarctica. These bottom layers were subdivided into two distinct facies: the lower 12 m showing visible solid inclusions (basal dispersed ice facies) and the upper 48 m, which we will refer to as the "basal clean ice facies". Some of the data are consistent with a pristine paleoclimatic signal, others show clear anomalies. It is demonstrated that neither large-scale bottom refreezing of subglacial water, nor mixing (be it internal or with a local basal end term from a previous/initial ice sheet configuration) can explain the observed bottom-ice properties. We focus on the high-resolution chemical profiles and on the available remote sensing data on the subglacial topography of the site to propose a mechanism by which relative stretching of the bottom-ice sheet layers is made possible, due to the progressively confining effect of subglacial valley sides. This stress field change, combined with bottom-ice temperature close to the pressure melting point, induces accelerated migration recrystallization, which results in spatial chemical sorting of the impurities, depending on their state (dissolved vs. solid) and if they are involved or not in salt formation. This chemical sorting effect is responsible for the progressive build-up of the visible solid aggregates that therefore mainly originate "from within", and not from incorporation processes of debris ... |
format |
Article in Journal/Newspaper |
author |
J.-L. Tison M. de Angelis G. Littot E. Wolff H. Fischer M. Hansson M. Bigler R. Udisti A. Wegner J. Jouzel B. Stenni S. Johnsen V. Masson-Delmotte A. Landais V. Lipenkov L. Loulergue J.-M. Barnola J.-R. Petit B. Delmonte G. Dreyfus D. Dahl-Jensen G. Durand B. Bereiter A. Schilt R. Spahni K. Pol R. Lorrain R. Souchez D. Samyn |
author_facet |
J.-L. Tison M. de Angelis G. Littot E. Wolff H. Fischer M. Hansson M. Bigler R. Udisti A. Wegner J. Jouzel B. Stenni S. Johnsen V. Masson-Delmotte A. Landais V. Lipenkov L. Loulergue J.-M. Barnola J.-R. Petit B. Delmonte G. Dreyfus D. Dahl-Jensen G. Durand B. Bereiter A. Schilt R. Spahni K. Pol R. Lorrain R. Souchez D. Samyn |
author_sort |
J.-L. Tison |
title |
Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core |
title_short |
Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core |
title_full |
Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core |
title_fullStr |
Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core |
title_full_unstemmed |
Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core |
title_sort |
retrieving the paleoclimatic signal from the deeper part of the epica dome c ice core |
publisher |
Copernicus Publications |
publishDate |
2015 |
url |
https://doi.org/10.5194/tc-9-1633-2015 https://doaj.org/article/cab145aa982247b4b545297f06bfa72b |
genre |
Antarc* Antarctica EPICA ice core Ice Sheet The Cryosphere |
genre_facet |
Antarc* Antarctica EPICA ice core Ice Sheet The Cryosphere |
op_source |
The Cryosphere, Vol 9, Iss 4, Pp 1633-1648 (2015) |
op_relation |
http://www.the-cryosphere.net/9/1633/2015/tc-9-1633-2015.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 1994-0416 1994-0424 doi:10.5194/tc-9-1633-2015 https://doaj.org/article/cab145aa982247b4b545297f06bfa72b |
op_doi |
https://doi.org/10.5194/tc-9-1633-2015 |
container_title |
The Cryosphere |
container_volume |
9 |
container_issue |
4 |
container_start_page |
1633 |
op_container_end_page |
1648 |
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1766269055742771200 |